At the moment I've got a lot of DB driven grid and record views and forms as the core functionality of the site is very bespoke in it's nature.

Added to that I currently have 70-80 pages of content (which are currently fairly static apart from some master pages for headers, footers, menus etc.

My boss would also like a CMS to control the content going forward. The site will initially launch with the content as static pages as described above.

But I'm going to have to go back and put a CMS on all the content. This presents a few choices as far as I can see:

1.) Bespoke CMSPros: Full flexibility over what control I give the customer. Seamless integration with the existing bespoke site I've already createdCons: Time/Effort to build. Ongoing support requirements.

2.) Off the Shelf/Open Source CMSPros: Lower support requirements, more features, power etc. etc.Cons: Challenges integrating with bespoke system already built (big things like session integration, menu integration from CMS on bespoke pages)

I'd really like to avoid scenario 1 if possible due to time/cost constraints.

My question is has anyone successfully implemented an off the shelf/open source CMS with existing custom bespoke functionality and if so, which one worked well?

IMO, the best solution would be to use a CMS for the whole thing, including the bespoke core funtionality. Then you could use the content from the bespoke functionality in the templates fro the normal content pages. And as a big bonus, you could edit the bespoke section data in the CMS interface as well. The only requirement would be to use a CMS that can store a data model that is powerful enough for your needs.